I had got into a battle with 3 trolls first to struck down with my chillrend and glass sword of blaze quite easy but the third went down and slowly got back up and just stood there breathing like he was still alive, i attacked him and nothing effected him, i could also search his body.... weird glitch...

I had a dead living frostbite spider once creeped me out

Yeah i had the same issue with a necromancer i think. it was weird